Ebay has a ton of cheap PIDs available for around $20 with thermocouple (model REX-C100 when that link dies). I'm wondering if I could use this to run a chest freezer as a fridge. I know when doing this you skip the SSR and just tie the freezer into the PID output. The specs say it's rated at 3a 250V. My question is if a small to mid size chest freezer running at 120V will be too much of a load?

The only thing that I do NOT like about that sale ad is that they really do not tell you a single thing about the pid. (Who makes it? The root specifications about it? A link to the data sheet on it? ...)

i.e. - you 'could' be good to go - or - you 'could' throw your money and time away.

IMHO - get devices that others have used and set up with success.

I really think that - that one is down the wrong path for you.

Another issue? Your time is money as well. A little more? Sooner? From a reliable resource?

A PID would be the wrong type of control for a freezer. It would short cycle the compressor and burn it out pretty quickly.

There are cheap ebay controllers that work well for freezer temp control, they include short-cycle protection timers. I use the STC-1000 and it's been working great for the past few months I've used it. Lots of info about it in the DIY section of the forum:

The SSR is a solid state relay that allows a low current rated device to control a high current load. In typical usage as a kettle element heater controller the PID (lowcurrent rated device) signals the SSR to allow power to the high current draw element to maintain a temperature.

My PID for boil kettle is set to a PWM cycle time of 4 seconds. I have my short-cycle timer on the freezer controller set to 10 minutes.

I'v been running one of my freezer chests off a cheap ebay PID for two years now. It works great. At first I tried to use a SSR and the PID, but the rapid cycling of the PID would not allow the compressor to turn on. The one I got has a 10A relay for the high temp alarm, so I wired the power supply for the compressor through the high temp alarm. No SSR needed.

from looking at the manual runningweird posted the alarm on this PID is rated at 1A for 250VAC (or is it 3A?) , so this PID might not work too well to run the compressor off the high temp alarm.

Personally it was more hassle than it was worth, and setting the temp is some what of a chore. I'd go with a $50 ranco controller . Ive bought 4 from these guys over the years.